In order to operate an integrated circuit, e.g., a microprocessor, in an efficient manner, for example, to consume a low amount of energy to accomplish a task, it is known to adjust various controlling parameters. These parameters may include an operating voltage or body-biasing voltage(s) that can be adjusted to a value characteristic of an advantageous power condition in accordance with the task to be accomplished. For example, an operating voltage is set to a minimized value consistent with a desired frequency of operation. Such controlling parameters are conventionally determined, e.g., via a lookup table, based upon characteristics of a manufacturing population of integrated circuits.
Unfortunately, numerous characteristics related to power consumption of an integrated circuit, e.g., a microprocessor, are highly variable across a manufacturing process. For example, maximum operating frequency, threshold voltage and capacitance may each vary by 30% or more, from batch to batch and even within the same wafer. Leakage current is exponential with threshold voltage and may vary by 500% from nominal. Conventional methods of determining controlling parameters are typically based upon the worst case operation of a population of processor devices, determined, e.g., during a qualification process, generally prior to general availability of the integrated circuit devices. Consequently, many or most of a manufactured population of integrated circuits are capable of more efficient operation. Unfortunately, such conventional methods of determining controlling parameters do not enable such enhanced efficient behavior from such integrated circuits.